﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.Threading;

using System.IO;

using Microsoft.DirectX;

using Microsoft.DirectX.DirectSound;
using System.Windows.Forms;

namespace Baidu.Sound.DirectSound
{
    public class SoundRecord
    {
        public const int cNotifyNum = 16;       // 缓冲队列的数目
        private int mNextCaptureOffset = 0;      // 该次录音缓冲区的起始点
        private int mSampleCount = 0;            // 录制的样本数目
        private int mNotifySize = 0;             // 每次通知大小
        private int mBufferSize = 0;             // 缓冲队列大小
        private string mFileName = string.Empty;     // 文件名
        private FileStream mWaveFile = null;         // 文件流
        private BinaryWriter mWriter = null;         // 写文件
        private Capture mCapDev = null;              // 音频捕捉设备
        private CaptureBuffer mRecBuffer = null;     // 缓冲区对象
        private Notify mNotify = null;               // 消息通知对象
        private WaveFormat mWavFormat;                       // 录音的格式
        private Thread mNotifyThread = null;                 // 处理缓冲区消息的线程
        private AutoResetEvent mNotificationEvent = null;    // 通知事件
        /// <summary>
        /// 构造函数,设定录音设备,设定录音格式.
        /// </summary>
        public SoundRecord()
        {
            // 初始化音频捕捉设备
            InitCaptureDevice();
            // 设定录音格式
            mWavFormat = CreateWaveFormat();
        }


        /// <summary>
        /// 设定录音结束后保存的文件,包括路径
        /// </summary>
        /// <param name="filename">保存wav文件的路径名</param>
        public void SetFileName(string filename)
        {
            mFileName = filename;
        }

        /// <summary>
        /// 开始录音
        /// </summary>
        public void RecStart()
        {
            // 创建录音文件
            CreateSoundFile();

            // 创建一个录音缓冲区，并开始录音
            CreateCaptureBuffer();

            // 建立通知消息,当缓冲区满的时候处理方法
            InitNotifications();

            mRecBuffer.Start(true);
        }

        /// <summary>
        /// 停止录音
        /// </summary>
        public void RecStop()
        {
            // 关闭通知消息
            if (null != mNotificationEvent)
                mNotificationEvent.Set();

            // 停止录音
            mRecBuffer.Stop();

            // 写入缓冲区最后的数据
            RecordCapturedData();

            // 回写长度信息
            mWriter.Seek(4, SeekOrigin.Begin);
            mWriter.Write((int)(mSampleCount + 36));   // 写文件长度
            mWriter.Seek(40, SeekOrigin.Begin);
            mWriter.Write(mSampleCount);                // 写数据长度

            mWriter.Close();
            mWaveFile.Close();
            mWriter = null;
            mWaveFile = null;
        }

        /// <summary>
        /// 初始化录音设备,此处使用主录音设备.
        /// </summary>
        /// <returns>调用成功返回true,否则返回false</returns>
        private bool InitCaptureDevice()
        {
            // 获取默认音频捕捉设备
            CaptureDevicesCollection devices = new CaptureDevicesCollection();  // 枚举音频捕捉设备
            Guid deviceGuid = Guid.Empty;                                       // 音频捕捉设备的ID

            if (devices.Count > 0)
                deviceGuid = devices[0].DriverGuid;
            else
            {
                MessageBox.Show("系统中没有音频捕捉设备");
                return false;
            }

                       
            // 用指定的捕捉设备创建Capture对象
            try
            {
                mCapDev = new Capture(deviceGuid);
            }
            catch (DirectXException e)
            {
                MessageBox.Show(e.ToString());
                return false;
            }
            return true;
        }
        /// <summary>
        /// 创建录音格式,此处使用16bit,16KHz,Mono的录音格式
        /// </summary>
        /// <returns>WaveFormat结构体</returns>
        private WaveFormat CreateWaveFormat()
        {

            WaveFormat format = new WaveFormat();

            format.FormatTag = WaveFormatTag.Pcm;   // PCM

            format.SamplesPerSecond = 16000;        // 16KHz

            format.BitsPerSample = 16;              // 16Bit

            format.Channels = 1;                    // Mono

            format.BlockAlign = (short)(format.Channels * (format.BitsPerSample / 8));

            format.AverageBytesPerSecond = format.BlockAlign * format.SamplesPerSecond;




            return format;

        }




        /// <summary>

        /// 创建录音使用的缓冲区

        /// </summary>

        private void CreateCaptureBuffer()
        {
            // 缓冲区的描述对象

            CaptureBufferDescription bufferdescription = new CaptureBufferDescription();




            if (null != mNotify)

            {

                mNotify.Dispose();

                mNotify = null;

            }

            if (null != mRecBuffer)

            {

                mRecBuffer.Dispose();

                mRecBuffer = null;

            }




            // 设定通知的大小,默认为1s钟

            mNotifySize = (1024 > mWavFormat.AverageBytesPerSecond / 8) ? 1024 : (mWavFormat.AverageBytesPerSecond / 8);

            mNotifySize -= mNotifySize % mWavFormat.BlockAlign;




            // 设定缓冲区大小

            mBufferSize = mNotifySize * cNotifyNum;




            // 创建缓冲区描述           

            bufferdescription.BufferBytes = mBufferSize;

            bufferdescription.Format = mWavFormat;           // 录音格式




            // 创建缓冲区

            mRecBuffer = new CaptureBuffer(bufferdescription, mCapDev);




            mNextCaptureOffset = 0;

        }




        /// <summary>

        /// 初始化通知事件,将原缓冲区分成16个缓冲队列,在每个缓冲队列的结束点设定通知点.

        /// </summary>

        /// <returns>是否成功</returns>

        private bool InitNotifications()

        {

            if (null == mRecBuffer)

            {

                MessageBox.Show("未创建录音缓冲区");

                return false;

            }




            // 创建一个通知事件,当缓冲队列满了就激发该事件.

            mNotificationEvent = new AutoResetEvent(false);




            // 创建一个线程管理缓冲区事件

            if (null == mNotifyThread)

            {

                mNotifyThread = new Thread(new ThreadStart(WaitThread));

                mNotifyThread.Start();

            }




            // 设定通知的位置

            BufferPositionNotify[] PositionNotify = new BufferPositionNotify[cNotifyNum + 1];

            for (int i = 0; i < cNotifyNum; i++)

            {

                PositionNotify[i].Offset = (mNotifySize * i) + mNotifySize - 1;

                PositionNotify[i].EventNotifyHandle = mNotificationEvent.Handle;

            }




            mNotify = new Notify(mRecBuffer);

            mNotify.SetNotificationPositions(PositionNotify, cNotifyNum);




            return true;

        }




        /// <summary>

        /// 将录制的数据写入wav文件

        /// </summary>

        private void RecordCapturedData()

        {

            byte[] CaptureData = null;

            int ReadPos;

            int CapturePos;

            int LockSize;




            mRecBuffer.GetCurrentPosition(out CapturePos, out ReadPos);

            LockSize = ReadPos - mNextCaptureOffset;

            if (LockSize < 0)

                LockSize += mBufferSize;




            // 对齐缓冲区边界,实际上由于开始设定完整,这个操作是多余的.

            LockSize -= (LockSize % mNotifySize);




            if (0 == LockSize)

                return;



            // 读取缓冲区内的数据

            CaptureData = (byte[])mRecBuffer.Read(mNextCaptureOffset, typeof(byte), LockFlag.None, LockSize);




            // 写入Wav文件

            mWriter.Write(CaptureData, 0, CaptureData.Length);




            // 更新已经录制的数据长度.

            mSampleCount += CaptureData.Length;




            // 移动录制数据的起始点,通知消息只负责指示产生消息的位置,并不记录上次录制的位置

            mNextCaptureOffset += CaptureData.Length;

            mNextCaptureOffset %= mBufferSize; // Circular buffer

        }




        /// <summary>

        /// 接收缓冲区满消息的处理线程

        /// </summary>

        private void WaitThread()

        {

            while (true)

            {

                // 等待缓冲区的通知消息

                mNotificationEvent.WaitOne(Timeout.Infinite, true);

                // 录制数据

                RecordCapturedData();

            }

        }




        /// <summary>

        /// 创建保存的波形文件,并写入必要的文件头.

        /// </summary>

        private void CreateSoundFile()

        {

            /**************************************************************************

         Here is where the file will be created. A

         wave file is a RIFF file, which has chunks

         of data that describe what the file contains.

         A wave RIFF file is put together like this:




         The 12 byte RIFF chunk is constructed like this:
         Bytes 0 – 3 :  'R' 'I' 'F' 'F'
         Bytes 4 – 7 :  Length of file, minus the first 8 bytes of the RIFF description.
                           (4 bytes for "WAVE" + 24 bytes for format chunk length +
                           8 bytes for data chunk description + actual sample data size.)
          Bytes 8 – 11: 'W' 'A' 'V' 'E'
          The 24 byte FORMAT chunk is constructed like this:
          Bytes 0 – 3 : 'f' 'm' 't' ' '
          Bytes 4 – 7 : The format chunk length. This is always 16.
          Bytes 8 – 9 : File padding. Always 1.
          Bytes 10- 11: Number of channels. Either 1 for mono,  or 2 for stereo.
          Bytes 12- 15: Sample rate.
          Bytes 16- 19: Number of bytes per second.
          Bytes 20- 21: Bytes per sample. 1 for 8 bit mono, 2 for 8 bit stereo or
                          16 bit mono, 4 for 16 bit stereo.
          Bytes 22- 23: Number of bits per sample.

          The DATA chunk is constructed like this:
          Bytes 0 – 3 : 'd' 'a' 't' 'a'
          Bytes 4 – 7 : Length of data, in bytes.
          Bytes 8 -…: Actual sample data.
                    ***************************************************************************/
            // Open up the wave file for writing.
            mWaveFile = new FileStream(mFileName, FileMode.Create);
            mWriter = new BinaryWriter(mWaveFile);
            // Set up file with RIFF chunk info.
            char[] ChunkRiff = { 'R', 'I', 'F', 'F' };
            char[] ChunkType = { 'W', 'A', 'V', 'E' };
            char[] ChunkFmt = { 'f', 'm', 't', ' ' };
            char[] ChunkData = { 'd', 'a', 't', 'a' };
            short shPad = 1;                // File padding
            int nFormatChunkLength = 0x10;  // Format chunk length.
            int nLength = 0;                // File length, minus first 8 bytes of RIFF description. This will be filled in later.
            short shBytesPerSample = 0;     // Bytes per sample.
            // 一个样本点的字节数目
            if (8 == mWavFormat.BitsPerSample && 1 == mWavFormat.Channels)
                shBytesPerSample = 1;
            else if ((8 == mWavFormat.BitsPerSample && 2 == mWavFormat.Channels) || (16 == mWavFormat.BitsPerSample && 1 == mWavFormat.Channels))
                shBytesPerSample = 2;
            else if (16 == mWavFormat.BitsPerSample && 2 == mWavFormat.Channels)
                shBytesPerSample = 4;
            // RIFF 块
            mWriter.Write(ChunkRiff);
            mWriter.Write(nLength);
            mWriter.Write(ChunkType);
            // WAVE块
            mWriter.Write(ChunkFmt);
            mWriter.Write(nFormatChunkLength);
            mWriter.Write(shPad);
            mWriter.Write(mWavFormat.Channels);
            mWriter.Write(mWavFormat.SamplesPerSecond);
            mWriter.Write(mWavFormat.AverageBytesPerSecond);
            mWriter.Write(shBytesPerSample);
            mWriter.Write(mWavFormat.BitsPerSample);
            // 数据块
            mWriter.Write(ChunkData);
            mWriter.Write((int)0);   // The sample length will be written in later.
        }
    }
}
